I think it should actually be blocks and tackle (block being count, tackle being non-count, so "two blocks and tackle" = "{two blocks} and {tackle [for each]}"). That said, Google seems to have a slight preference for block and tackles. The intermediate blocks and tackles does not seem to be popular at all (it fairs O.K., hit-count-wise, but few of the hits are in this sense). Other phrasings, like block and tackle systems and block and tackle balances, also seem to be in currency (as do their normal singulars). None of these seems anywhere near as popular as the singular block and tackle, suggesting either that this is usually used in the singular, or that the usual plural is something I haven't thought of. —RuakhTALK 17:04, 12 September 2007 (UTC)

Isn't the compound block and tackle itself uncountable? Are you sure the uses of "blocks and tackle" that come up on Google aren't simply erroneous? --Connel MacKenzie 17:27, 12 September 2007 (UTC)

I really don't think it can be uncountable — "a {block and tackle}" seems quite well-formed — but it might only exist in the singular. (Another such, for some speakers, is "mouse", in the computer sense: clearly "mouse" is countable and singular, but many speakers simply do not pluralize it, instead going with something like "mouse devices".) —RuakhTALK 19:26, 12 September 2007 (UTC)

So you disagree with the references I provided below? Interesting, but not particularly useful. It is important to indicate that it is uncountable first; many (obviously not just me) consider the "pluralizing" of it, to be incorrect. Indicating an incorrect plural form as an alternate (with its own warning) seems warranted, given how many errors turn on up your Google search. --Connel MacKenzie 19:40, 12 September 2007 (UTC)

Re: "So you disagree with the references I provided below?": Not at all. I think you must have misunderstood my comment? —RuakhTALK 20:03, 12 September 2007 (UTC)

I guess so. Perhaps you could rephrase "I really don't think it can be uncountable"? --Connel MacKenzie 20:10, 12 September 2007 (UTC)

Hmm. I think maybe we're defining "uncountable" differently? You seem to be using it to mean "lacking a plural"; for me, while an uncountable noun certainly lacks a plural, that's not enough to make a noun uncountable. For me, a noun like salt is uncountable, because you can't say *"a salt". You can, however, say "a block and tackle", even if it doesn't have a plural like "block and tackles" or "blocks and tackle" or something. (I'm not sure if the word "uncountable" is ambiguous between these two senses, or if one of us is using it mistakenly.) —RuakhTALK 20:20, 12 September 2007 (UTC)

I think the plural is most commonly formed indirectly... "sets of block and tackle," "block and tackle mechanisms," etc. Google Patents turns up as many of these forms as you could desire... Which doesn't help us terribly, though it does suggest that (as Connel points out above) this phrase may actually be uncountable. What concerns me about "blocks and tackle" is that it (and for that matter "blocks and tackles") arguably could refer to a single set (since by definition a block and tackle consists of at least two pulleys) -- so it may, at least in some cases, just be an alternate form of the singular.

I mean, at least according to the current definition, you couldn't say "two blocks and tackle" to refer to two separate b&t setups, because each setup already contains at least two blocks. (I'm not sure if that definition is strictly correct; my real-life winching experience has been rather limited and less than successful.) On the other hand, you could theoretically say (as some people clearly do) "two block-and-tackles." -- Visviva 17:48, 12 September 2007 (UTC)

Digging just a little deeper, [1], [2], [3] and [4] all list it as singular, describing plurals. On the other hand, this lists it with the doubly-erroneous plural (so I think they just had a bad day or something, when writing it.) I know I would only write "block and tackle" to describe multiple block and tackle assemblies. --Connel MacKenzie 17:51, 12 September 2007 (UTC)